The Storm Brewing in Michigan

With its rich, dark wood, golden décor, and an invigorating oud musk, the American Moslem Society on the south end of Dearborn, Michigan, masks its age well. Opened in 1937, it was the first mosque in America to broadcast the call to prayer through loudspeakers. It was founded by Arab immigrants who had initially been drawn by the promise of $5-a-day jobs at a nearby Ford plant, which laid the foundation for what is now America’s largest concentration of Arab Americans.

On a recent Friday there, an imam clad in...